Pension and Other Postretirement Benefits Narrative (Details)	6 Months Ended
Jan. 31, 2019 USD ($)
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans
Employer contributions	$ 0
Estimated contributions in remainder of current fiscal year	$ 0
Postretirement Health Plan
Defined Benefit Plans and Other Postretirement Benefit Plans
Medical Cost Trend Assumption	7.50%
Ultimate Health Care Cost Trend Rate	4.50%
Year that Rate Reaches Ultimate Trend Rate	2038

Amount of contribution received by defined benefit plan from employer which increases plan assets.

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Amount of contributions expected to be received by defined benefit plan from employer in fiscal year. Excludes contributions paid by employer in current fiscal year.

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Assumed rate, for next fiscal year, based on annual change in cost of health care cost benefits used to measure expected cost of benefits covered by defined benefit postretirement plan. Factors include, but are not limited to, estimate of health care inflation, change in health care utilization or delivery pattern, technological advances, and change in health status of participant. Excludes factors for change in composition of plan population by age and dependency status.

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Ultimate trend rate for health care cost for defined benefit postretirement plan.

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Year ultimate health care cost trend rate is expected to be reached, in CCYY format.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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